More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is
- more active nature of the actinoids
- more energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
- lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
- greater metallic character of the lanthanoids than that of the corresponding actinoids.
Answer
(3) lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
Solution
As per NCERT, the actinoids show a greater range of oxidation states because the 5f, 6d and 7s levels are of comparable energies.
∵ The energy gap between 5f and 6d orbitals is smaller than that between 4f and 5d orbitals, electrons from both 5f and 6d can take part in bonding.
∴ Actinoids exhibit more oxidation states than lanthanoids.
Answer: (3)